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1 | /* |
2 | * Codel - The Controlled-Delay Active Queue Management algorithm |
3 | * |
4 | * Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com> |
5 | * Copyright (C) 2011-2012 Van Jacobson <van@pollere.net> |
6 | * |
7 | * Implemented on linux by : |
8 | * Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net> |
9 | * Copyright (C) 2012 Eric Dumazet <edumazet@google.com> |
10 | * |
11 | * Redistribution and use in source and binary forms, with or without |
12 | * modification, are permitted provided that the following conditions |
13 | * are met: |
14 | * 1. Redistributions of source code must retain the above copyright |
15 | * notice, this list of conditions, and the following disclaimer, |
16 | * without modification. |
17 | * 2. Redistributions in binary form must reproduce the above copyright |
18 | * notice, this list of conditions and the following disclaimer in the |
19 | * documentation and/or other materials provided with the distribution. |
20 | * 3. The names of the authors may not be used to endorse or promote products |
21 | * derived from this software without specific prior written permission. |
22 | * |
23 | * Alternatively, provided that this notice is retained in full, this |
24 | * software may be distributed under the terms of the GNU General |
25 | * Public License ("GPL") version 2, in which case the provisions of the |
26 | * GPL apply INSTEAD OF those given above. |
27 | * |
28 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
29 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
30 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
31 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
32 | * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
33 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
34 | * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
35 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
36 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
37 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
38 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH |
39 | * DAMAGE. |
40 | * |
41 | */ |
42 | |
43 | #include <linux/module.h> |
44 | #include <linux/slab.h> |
45 | #include <linux/types.h> |
46 | #include <linux/kernel.h> |
47 | #include <linux/errno.h> |
48 | #include <linux/skbuff.h> |
49 | #include <linux/prefetch.h> |
50 | #include <net/pkt_sched.h> |
51 | #include <net/codel.h> |
52 | |
53 | |
54 | #define DEFAULT_CODEL_LIMIT 1000 |
55 | |
56 | struct codel_sched_data { |
57 | struct codel_params params; |
58 | struct codel_vars vars; |
59 | struct codel_stats stats; |
60 | u32 drop_overlimit; |
61 | }; |
62 | |
63 | /* This is the specific function called from codel_dequeue() |
64 | * to dequeue a packet from queue. Note: backlog is handled in |
65 | * codel, we dont need to reduce it here. |
66 | */ |
67 | static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch) |
68 | { |
69 | struct sk_buff *skb = __skb_dequeue(&sch->q); |
70 | |
71 | prefetch(&skb->end); /* we'll need skb_shinfo() */ |
72 | return skb; |
73 | } |
74 | |
75 | static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch) |
76 | { |
77 | struct codel_sched_data *q = qdisc_priv(sch); |
78 | struct sk_buff *skb; |
79 | |
80 | skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue); |
81 | |
82 | /* We cant call qdisc_tree_decrease_qlen() if our qlen is 0, |
83 | * or HTB crashes. Defer it for next round. |
84 | */ |
85 | if (q->stats.drop_count && sch->q.qlen) { |
86 | qdisc_tree_decrease_qlen(sch, q->stats.drop_count); |
87 | q->stats.drop_count = 0; |
88 | } |
89 | if (skb) |
90 | qdisc_bstats_update(sch, skb); |
91 | return skb; |
92 | } |
93 | |
94 | static int codel_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch) |
95 | { |
96 | struct codel_sched_data *q; |
97 | |
98 | if (likely(qdisc_qlen(sch) < sch->limit)) { |
99 | codel_set_enqueue_time(skb); |
100 | return qdisc_enqueue_tail(skb, sch); |
101 | } |
102 | q = qdisc_priv(sch); |
103 | q->drop_overlimit++; |
104 | return qdisc_drop(skb, sch); |
105 | } |
106 | |
107 | static const struct nla_policy codel_policy[TCA_CODEL_MAX + 1] = { |
108 | [TCA_CODEL_TARGET] = { .type = NLA_U32 }, |
109 | [TCA_CODEL_LIMIT] = { .type = NLA_U32 }, |
110 | [TCA_CODEL_INTERVAL] = { .type = NLA_U32 }, |
111 | [TCA_CODEL_ECN] = { .type = NLA_U32 }, |
112 | }; |
113 | |
114 | static int codel_change(struct Qdisc *sch, struct nlattr *opt) |
115 | { |
116 | struct codel_sched_data *q = qdisc_priv(sch); |
117 | struct nlattr *tb[TCA_CODEL_MAX + 1]; |
118 | unsigned int qlen; |
119 | int err; |
120 | |
121 | if (!opt) |
122 | return -EINVAL; |
123 | |
124 | err = nla_parse_nested(tb, TCA_CODEL_MAX, opt, codel_policy); |
125 | if (err < 0) |
126 | return err; |
127 | |
128 | sch_tree_lock(sch); |
129 | |
130 | if (tb[TCA_CODEL_TARGET]) { |
131 | u32 target = nla_get_u32(tb[TCA_CODEL_TARGET]); |
132 | |
133 | q->params.target = ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT; |
134 | } |
135 | |
136 | if (tb[TCA_CODEL_INTERVAL]) { |
137 | u32 interval = nla_get_u32(tb[TCA_CODEL_INTERVAL]); |
138 | |
139 | q->params.interval = ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT; |
140 | } |
141 | |
142 | if (tb[TCA_CODEL_LIMIT]) |
143 | sch->limit = nla_get_u32(tb[TCA_CODEL_LIMIT]); |
144 | |
145 | if (tb[TCA_CODEL_ECN]) |
146 | q->params.ecn = !!nla_get_u32(tb[TCA_CODEL_ECN]); |
147 | |
148 | qlen = sch->q.qlen; |
149 | while (sch->q.qlen > sch->limit) { |
150 | struct sk_buff *skb = __skb_dequeue(&sch->q); |
151 | |
152 | sch->qstats.backlog -= qdisc_pkt_len(skb); |
153 | qdisc_drop(skb, sch); |
154 | } |
155 | qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen); |
156 | |
157 | sch_tree_unlock(sch); |
158 | return 0; |
159 | } |
160 | |
161 | static int codel_init(struct Qdisc *sch, struct nlattr *opt) |
162 | { |
163 | struct codel_sched_data *q = qdisc_priv(sch); |
164 | |
165 | sch->limit = DEFAULT_CODEL_LIMIT; |
166 | |
167 | codel_params_init(&q->params); |
168 | codel_vars_init(&q->vars); |
169 | codel_stats_init(&q->stats); |
170 | |
171 | if (opt) { |
172 | int err = codel_change(sch, opt); |
173 | |
174 | if (err) |
175 | return err; |
176 | } |
177 | |
178 | if (sch->limit >= 1) |
179 | sch->flags |= TCQ_F_CAN_BYPASS; |
180 | else |
181 | sch->flags &= ~TCQ_F_CAN_BYPASS; |
182 | |
183 | return 0; |
184 | } |
185 | |
186 | static int codel_dump(struct Qdisc *sch, struct sk_buff *skb) |
187 | { |
188 | struct codel_sched_data *q = qdisc_priv(sch); |
189 | struct nlattr *opts; |
190 | |
191 | opts = nla_nest_start(skb, TCA_OPTIONS); |
192 | if (opts == NULL) |
193 | goto nla_put_failure; |
194 | |
195 | if (nla_put_u32(skb, TCA_CODEL_TARGET, |
196 | codel_time_to_us(q->params.target)) || |
197 | nla_put_u32(skb, TCA_CODEL_LIMIT, |
198 | sch->limit) || |
199 | nla_put_u32(skb, TCA_CODEL_INTERVAL, |
200 | codel_time_to_us(q->params.interval)) || |
201 | nla_put_u32(skb, TCA_CODEL_ECN, |
202 | q->params.ecn)) |
203 | goto nla_put_failure; |
204 | |
205 | return nla_nest_end(skb, opts); |
206 | |
207 | nla_put_failure: |
208 | nla_nest_cancel(skb, opts); |
209 | return -1; |
210 | } |
211 | |
212 | static int codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d) |
213 | { |
214 | const struct codel_sched_data *q = qdisc_priv(sch); |
215 | struct tc_codel_xstats st = { |
216 | .maxpacket = q->stats.maxpacket, |
217 | .count = q->vars.count, |
218 | .lastcount = q->vars.lastcount, |
219 | .drop_overlimit = q->drop_overlimit, |
220 | .ldelay = codel_time_to_us(q->vars.ldelay), |
221 | .dropping = q->vars.dropping, |
222 | .ecn_mark = q->stats.ecn_mark, |
223 | }; |
224 | |
225 | if (q->vars.dropping) { |
226 | codel_tdiff_t delta = q->vars.drop_next - codel_get_time(); |
227 | |
228 | if (delta >= 0) |
229 | st.drop_next = codel_time_to_us(delta); |
230 | else |
231 | st.drop_next = -codel_time_to_us(-delta); |
232 | } |
233 | |
234 | return gnet_stats_copy_app(d, &st, sizeof(st)); |
235 | } |
236 | |
237 | static void codel_reset(struct Qdisc *sch) |
238 | { |
239 | struct codel_sched_data *q = qdisc_priv(sch); |
240 | |
241 | qdisc_reset_queue(sch); |
242 | codel_vars_init(&q->vars); |
243 | } |
244 | |
245 | static struct Qdisc_ops codel_qdisc_ops __read_mostly = { |
246 | .id = "codel", |
247 | .priv_size = sizeof(struct codel_sched_data), |
248 | |
249 | .enqueue = codel_qdisc_enqueue, |
250 | .dequeue = codel_qdisc_dequeue, |
251 | .peek = qdisc_peek_dequeued, |
252 | .init = codel_init, |
253 | .reset = codel_reset, |
254 | .change = codel_change, |
255 | .dump = codel_dump, |
256 | .dump_stats = codel_dump_stats, |
257 | .owner = THIS_MODULE, |
258 | }; |
259 | |
260 | static int __init codel_module_init(void) |
261 | { |
262 | return register_qdisc(&codel_qdisc_ops); |
263 | } |
264 | |
265 | static void __exit codel_module_exit(void) |
266 | { |
267 | unregister_qdisc(&codel_qdisc_ops); |
268 | } |
269 | |
270 | module_init(codel_module_init) |
271 | module_exit(codel_module_exit) |
272 | |
273 | MODULE_DESCRIPTION("Controlled Delay queue discipline"); |
274 | MODULE_AUTHOR("Dave Taht"); |
275 | MODULE_AUTHOR("Eric Dumazet"); |
276 | MODULE_LICENSE("Dual BSD/GPL"); |
277 |
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